1. Field of the Invention
The present invention relates generally to propulsion systems for marine vessels, and more particularly to a marine propulsion unit for shallow and obstructed water operation and the various components thereof.
2. Description of the Related Art
There are various marine propulsion systems available today, the majority of which utilize a propeller to rotationally cut through the water in a helical manner, propelling the marine vessel at a speed proportional to the rotational speed of the propeller. There are also jet driven craft that use a pump to squirt a jet of water out the rear of the vessel to propel it forward, often very quickly. Both of these propulsion systems are prone to damage when operated in shallow or obstructed water. Often shallow water contains debris including branches, logs, rocks, weeds, and other obstacles that can quickly damage both propeller and jet driven vessels. As a result most boat operators do not venture into shallow, swampy, marshy, or otherwise obstructed water. While simply avoiding these water areas may not be a burden for many boaters, those that hunt, fish or engage in many other outdoor activities often find these generally non-navigable areas to be prime areas to access, if only there were a way to safely do so. In an attempt to fill this need, airboats came about. An airboat is a generally flat bottomed boat with a large engine attached to an aircraft style propeller. Since there are no moving parts below the water line, this style of boat is suitable for swampy, shallow and obstructed areas. Despite their usefulness, airboats are exceedingly loud, and are expensive to purchase and operate. As a result, various styles of what are commonly referred to as mud motors currently exist. Mud motors are attached to a flat bottomed boat such as a john boat, and look similar to an outboard motor, but have a long shaft with a propeller on the distal end that can be angled into or out of the water. This allows the propeller to spin in a partially submerged state, with the depth dependent on the type of obstructions encountered. For example, thick swamp like conditions would require the operator to move the drive shaft upward, in effect skimming across the weed and plant growth. Since the drive shaft of a mud motor must be angled by the operator based on the conditions encountered, operator fatigue often occurs. In addition, since the propeller is not always totally submerged, unsafe conditions can easily occur. One such condition occurs when the mud boat strikes a submerged or otherwise unseen obstacle and the operator is ejected from the boat. The torque of the mud motor will cause the now operator-less boat to drive in circles, repeatedly running over the operator who has been thrown from the boat. This condition, known by some as the circle of death, is one of the known risks of using many of the various mud motors. In addition, a mud motor is typically not well suited for traditional deep water operation, making it a specialty item with limited applicability. Current, mud motors are custom manufactured, on a very small scale compared with mass produced outboard motors, making replacement parts costly and the continued availability of replacement parts an ongoing concern.
What is needed is a marine propulsion unit for shallow and obstructed water operation that is safe, can also be used for traditional deep water operation, and incorporates a standard outboard motor.
It is thus an object of the present invention to provide such a marine propulsion unit as will be further described herein. These and other objects of the present invention are not to be considered comprehensive or exhaustive, but rather, exemplary of objects that may be ascertained after reading this specification and claims with the accompanying drawings.